We do not want to edit the content according to Yoast SEO plugin focus keyword. Can searching for our website in Google be effective without doing so?
The Yoast SEO keyword focus feature is there to help you gauge how strong your on-page content is as it relates to the keyword you want the page to rank for. However, it is not the only truth for ranking your pages, and the keyword focus is not the only thing that determines where your page is ranked. (And has nothing to do with whether the page is in the index.) It is only a tool that aims to be helpful with one aspect of content SEO.
An experienced content producer or SEO may not even need this feature turned on. Building and optimizing sites for clients, I have found that novices benefited from this feature much more than experienced content marketers, who ended up ignoring it and even asking me to turn it off. Newer marketers told me it was nice to have.
Your page ranking in the SERPs depends on many factors, including metadata, mobile friendliness, information architecture of the website, site speed, the context of your content, links profiles, and yes, keywords. You know your content better than Yoast. Produce what makes sense for your website, and use Yoast as more a suggestion than a hard truth.
If you don't want to do something - just don't do it, nobody forces you to. This is a question of your very private opinion and is absolutely misplaced here.
The question would better match the goals of this site is rather something like "would you recommend to make an additional keyword research and/or LSI analysis of certain text along to recommendation of Yoast plugin".
The answer to this question would be: it depends from the language and the kind of your text. In English and on texts to not very special topics Yoast delivers pretty good recommendations. If you have much content, try to set priorities - for content you expect more from, do research by yourself, for content you don't expect much - trust Yoast.